A hearing instrument or hearing aid is a device for amplification of sound or acoustic (audio) signals. A hearing aid may be worn at or behind an ear of a person having compromised hearing capabilities. The amplification of the acoustic signals may be performed by an electronic circuit requiring electric energy. The electric energy may be taken from a battery or an accumulator comprised in the hearing aid. Depending on a usage of the hearing aid the energy in the battery or the accumulator may be reduced over time requiring to either replace the empty battery with a charged battery or to charge the accumulator. Nowadays, the majority of hearing instruments or hearing aids in the market still have batteries which are not rechargeable and which have to be replaced weekly or biweekly. In particular, for elder people replacement of the often tiny batteries is difficult, since the elder people often are not very skilled to handle tiny batteries. Further, the battery door occupies space in the hearing aid which may limit miniaturization and may limit also battery capacity.
Alternatively, when the hearing aid is equipped with a rechargeable battery or accumulator, the accumulator is typically taken out of the hearing aid presenting essentially similar problems as known rechargeable batteries.
U.S. Pat. No. 4,379,988 discloses a moulded hearing aid and battery charger, wherein the hearing aid comprising an accumulator may be placed into a cup having a wire wound around the cup for charging the accumulator of the hearing aid.
US 2002/0113572 A1 discloses a wireless battery charging system for existing hearing aids, wherein a dynamic battery comprising a battery component and an inductor component may be placed close to a coil of a charging station for charging the battery component. The dynamic battery essentially comprises a battery component and an inductor component formed by a wire wound around the battery component and further comprising an electronic circuit.
The solutions known from the prior art for transferring energy to a hearing aid or generally for transferring energy to an accumulator are often not easily integrated in miniaturized hearing instruments and often do not have capabilities for effectively charging the accumulator.
There may be a need for an apparatus for transferring energy to an accumulator which is improved regarding efficiency and which at the same time is suitable to be integrated in a hearing instrument. Further, there may be a need for an apparatus for transferring energy to an accumulator which can easily be handled even by elderly persons.
According to embodiments Magnetic Induction (MI) technology is utilized. MI is known to be a low-power communications solution for RFID, Near Field Communications (NFC), Wireless Body Area Networks (WBAN), and has been applied in wireless headsets (AuraComm LibertyLink, FreeLinc) and hearing aids (Phonak, using NXP's MI Radio technology). According to embodiments Magnetic Induction (MI) technology is utilized for inductive charging of an accumulator comprised in hearing aid.